prepare('SELECT * FROM student_exams WHERE id = ? AND student_id = ?');
$stmt->execute([$student_exam_id, $user_id]);
$student_exam = $stmt->fetch();
if (!$student_exam) {
echo "You are not assigned to this exam.";
exit();
}
// Prevent re-taking a completed exam
if ($student_exam['status'] === 'completed') {
echo "You have already completed this exam.";
// Maybe redirect to a results page in the future
echo ' Back to Exams';
exit();
}
// Fetch exam details
$stmt = $pdo->prepare('SELECT * FROM exams WHERE id = ?');
$stmt->execute([$student_exam['exam_id']]);
$exam = $stmt->fetch();
// Fetch exam questions
$stmt = $pdo->prepare('SELECT * FROM exam_questions WHERE exam_id = ? ORDER BY id ASC');
$stmt->execute([$exam['id']]);
$questions = $stmt->fetchAll();
// Handle exam submission
if ($_SERVER['REQUEST_METHOD'] === 'POST' && isset($_POST['answers'])) {
$answers = $_POST['answers'];
$pdo->beginTransaction();
try {
foreach ($answers as $question_id => $answer_text) {
// Use INSERT ... ON DUPLICATE KEY UPDATE to prevent duplicate answer submissions
$sql = 'INSERT INTO student_answers (student_exam_id, question_id, answer_text) VALUES (?, ?, ?) ON DUPLICATE KEY UPDATE answer_text = VALUES(answer_text)';
$stmt = $pdo->prepare($sql);
$stmt->execute([$student_exam_id, $question_id, trim($answer_text)]);
}
// Mark exam as completed
$stmt = $pdo->prepare('UPDATE student_exams SET status = \'completed\' WHERE id = ?');
$stmt->execute([$student_exam_id]);
$pdo->commit();
header('Location: exams.php');
exit();
} catch (Exception $e) {
$pdo->rollBack();
// Log error properly in a real application
die("An error occurred while submitting your exam. Please try again. Error: " . $e->getMessage());
}
}
// If student is starting the exam, mark it as 'in-progress'
if ($student_exam['status'] === 'assigned') {
$stmt = $pdo->prepare('UPDATE student_exams SET status = \'in-progress\' WHERE id = ?');
$stmt->execute([$student_exam_id]);
}
?>
Take Exam: <?php echo htmlspecialchars($exam['name']); ?>